This invention relates to the art of venting and, more particularly, to venting of air from a chamber through holes which are restricted by vent plugs. Although the invention is particularly applicable for use in chambers for manufacturing sand molds by a blow-squeeze process and will be described with specific reference thereto, it will be appreciated that the invention has broader aspects, and may be used in other environments for other purposes.
Sand molds are commonly manufactured by blowing sand onto a pattern located within a chamber from which the air is vented in a controlled manner for properly distributing and packing the sand in the pattern. The location and number of vent openings achieve proper or predetermined distribution of the sand. The vents are defined by holes or passages extending through the walls of the chamber which, in turn, are restricted by vent plugs. The outlet vent passages thus defined are dimensioned to be smaller than the sand particle size so that substantially all of the sand will remain in the chamber.
However, and notwithstanding the foregoing dimensional relationships, there is a considerable amount of dust or sand fines which pass through the restricted vent passages and build up on the passage walls. The build-up of these deposits restricts the vent passages to such an extent that the sand will not be properly distributed throughout the pattern, and the sand mold thereafter produced may have insufficient density due to excessive entrained air. Therefore, frequent removal of the vent plugs and cleaning of the vent passages is necessary for production of satisfactory sand molds.
It has been considered desirable to develop a vent plug arrangement that would minimize build-up of deposits on the walls of the vent passages. The subject invention is believed to meet these needs and others in providing a vent plug having a new and novel conformation.